You will probably find that as most people do, you'll need to apply to many schemes many times, and whilst you should put every effort you can into preparing, not letting it distract from your plan in life which should be to fund your own training as far as possible (if you really want to do this as a job). Each time you apply you will improve and learn something new.
It is hard to comprehend how low the odds are on some schemes, so do your best but never presume you will end up with the golden ticket until maybe some day you do - most people do not get a place on these schemes until applying several times. You should see the first few attempts as learning opportunities to allow you to turn up the next year better prepared.